The present invention relates to a process for the preparation of a cohesive mass of herring eggs from loose herring eggs, particularly the loose eggs of the (North) Atlantic herring.
Herring can be found in cold northerly waters, such as those of the Pacific ocean, the Atlantic ocean, the Bering sea, the Baltic sea, the irish sea, Barents sea, the sea of Japan, the Okhotsk sea, the Yellow sea, the East china sea, the Norwegian sea, the North sea, the Korean sea and the East Siberian sea. Thus, for example, herring is caught in the North Pacific area along the west coasts of the United States and Canada; herring is also caught in the North Atlantic area along the east coasts of the United States and Canada, such as for example off the coast of the New England states and the Maritime provinces of eastern Canada (e.g. Newfoundland).
The whole ovary of Pacific herring is eaten in Japan as salt cured herring roe. The cured Pacific herring ovary or roe is known in Japan as salted "kazunoko". Kazunoko is prepared by soaking the mature whole ovaries (containing eggs) of Pacific herring in a salt solution to thereby cure and form the eggs into a hardened aggregation. Kazunoko is highly prized in Japan and is used as an expensive, gourmet food which is very popular during the New Year holiday season.
Although the herring in the above mentioned areas are all of the same family the ovary of herring caught in one area does not necessarily have the same characteristics as the ovary of herring caught in another. Thus, for example, the ovary of the Pacific herring (Clupea pallashii) is different from the ovary of Atlantic herring (Clupea harengus). Both the ovarial membrane and the cohesive character of the eggs differ greatly between Pacific and Atlantic herring. The ovarial membrane of Atlantic herring is relatively weak and the membrane is easily broken when being extracted from the fish; accordingly, it is very difficult to obtain satisfactory whole ovaries of Atlantic herring on a commercial scale since the tendency is for the ovaries to break open and for the eggs to spill out as loose herring eggs. Additionally, eggs of the Atlantic herring possess a relatively low degree of cohesiveness as compared to the eggs of Pacific herring. As a result, while whole Pacific herring ovaries are easily processed into cured herring roe suited for Japanese consumption, the ovary and eggs of the Atlantic herring are generally wasted because there is presently no efficient process for processing them into expensive "kazunoko" or a "kazunoko"-type food item comparable to that obtained from Pacific herring. The ovaries and loose eggs of Atlantic herring thus have a very low commercial value.
Various attempts have heretofore been made to process loose herring eggs.
Thus, for example, Canadian patent no. 1,099,142 teaches a method of processing loose eggs of Atlantic herring into a coherent or cohesive product. The process as taught by this patent requires that fresh loose eggs must first be de-blooded by being washed with (fresh, i.e. unsalted) water; thereafter the (fresh) water washed eggs are drained, placed into a container having the desired shape and subjected to a series of three to five soakings in salt solutions of different concentrations, the salt (i.e. sodium chloride) concentrations ranging upwardly from a least 8% of saturation in the initial stage to the saturation level in the final stage; it is to be understood herein that the percentage concentration of salt is given in terms of a percentage of the salt concentration at the saturation level of salt dissolved in water. Each soaking, including the initial soaking, is taught as extending over a relatively prolonged period of time (e.g. from 20 to 24 hours or longer). The process as taught by this patent is thus relatively complicated (i.e. it requires that the eggs be fresh water washed and then be transferred between a plurality of solutions of different salt concentration); the process as taught by this Canadian patent is also relatively time consuming (i.e. it may take from three to ten days to obtain a finished product). Additionally, the process as taught requires that the herring eggs be fresh; this may put an excessive burden on any herring egg processing facility during the usual fishing season (1-1.5 months) while leaving the plant idle the rest of the time.
Accordingly, it would be advantageous to have a less complicated and time consuming process whereby the loose eggs of herring (e.g. Atlantic herring, Pacific herring, Baltic sea herring and the like) may be processed into a cohesive mass of cured herring eggs which possesses a crispness the same as or approaching that of salted kazunoko obtained from whole Pacific herring ovaries and which could thus be sold at prices approaching that of kazunoko prepared from the ovary of the Pacific herring.
It would also be advantageous to have a process whereby the herring eggs need not be more or less immediately processed after the fish is caught and which would still provide a cohesive mass of cured herring eggs which possesses a crispness the same as or approaching that of salted kazunoko obtained from whole Pacific herring ovaries.